Thermocouple mounting for furnaces



'W. B. LEVY THERMQ-COUPLE MOUNTING FOR FURNACES Aug. 14, 1945.

Filed Jan 23, 1943 Patented Aug. 14, 1945 UNITED. STATES THERMOCOUPLE MOUNTING FOR FURNACES William B. Levy, Wilmington, Del. I Application January 23, 1943, Serial No. 473,380

4 Claims.

This invention relates to metal-heating furnaces; and more particularly to furnaces of the mufile type, as disclosed in United States Letters Patent, No. 2,277,595, issued March 24, 1942, to

William B. Levy (the present applicant) and 4, suitably secured together to provide an integral 7 structure.

The shell I houses a body of heat-insulating material 5, in the center of which is located the combustion chamber of the furnace, the front and back plates of which support the muflie of the furnace.

The mufile is heated by a swirling sheet of flame revolving about the axis of the mufile, externally thereof, within the combustion chamber, as disclosed in the aforesaid patent. Atmosphere for treating the work specimens being heated in the muflle is supplied thereto through a port formed 'by a tube extending through the back wall of the furnace.

Heretofore, the temperature of the interior of the muflle has been constantly determined andregistered by use of a thermo-couple device projecting through the back wall |3 of the furnace and the back wall |8 of the muflle, with the inner end of the thermo-couple device projecting axially of and into the muffle a predetermined distance from the back wall l8 thereof.

As shown more particularly in Fig. 1, the thermo-couple device 20 is of a commercially obtainable type and includes a ceramic tube 2|, composed of sillimanite, porcelain, etc. within which is located the couple, in the form of one or more relatively fine gauge wires (not shown). The free end 22 of the tube 2| is closed to seal the .thermo-sensitive element therein. The opposite end 23 of the tube 2| snugly fits into one end of a tapering, externally threaded standard pipe bushing 24, and is firmly secured therein. Threaded into the opposite end of the bushing 24 is the neck portion 25a of the base 25 of the thermo-couple device, in which latter are housed.

the mechanical and/orelectrical terminals of the couple, to which the thermo-sensit'ive wires are connected.

The present'inve'ntio'n is not concerned with the detai1 structure of. the 'thermo couple device 20, except in sofar as the device 20 includes the metallic-base 25, the bushing- 24 which serves as a shank for said base; and the ceramic tube-2| projecting from and axially therewith, With the long thin body portionof the tube .extendingbeyondthe screw threaded bushing 24 which .constitutes the terminal end or shank of the metal base structure 25. i l

Heretofore, the therr'n'o-couple'device 20 has been inserted through ahole 26 formed in" the insulatingmaterial 5 in the back wall l3'of the furnace, and through anax-ially aligned hole '21 formed ,in the back wall. l8 of themuflle. The back plate 4 of the furnace-normally was provided with a screw threaded opening 28, into which the tapered vbushing 24 of the vbas'e25 of the thermocouple deviceZU was screwed, by'm'eans of a wrench applied directly to a hexagonal portion 29 of the bushing 24." x

vThe above noted structure was satisfactory when the thermo-coupledevice was being initially appliedto 'the'assembled furnace,'il e., before operation of the furnace. During subsequent'use of the furnace, which operates at temperatures ranging as high as 2500 F.,' the tube 2|, in many instances, became warped or cracked cross-sectionally; Inmost instances, the opening 21 around the tube 2| is closed and sealed with'a refractory insulation which ha'rdens under the high operating temperatures of the furnace and holds the tube securely in the furnace wall.

.If at any time afterin'stallation, it b'ecame necessary,'for any reason whatsoever, to remove-the thermo-couple device 20 from the furnace, rotation of the device as a unit was necessary, by applying a wrench to'the hexagonal portion '29 thereof, in order to back thebushin'g 24 out of the threaded opening 28 in theback plate 4 of the furnace, consequently any'axial deformation or misalignment of the tube 2|, as' the tube was rotated within theopenings 26 and 21, caused the tube 2| and the thermo-sensitive wires within the tube to break, rendering the couple useless.

The object of the present invention is to eliminate all necessity for'rotating the device 20 in a furnace wall during either the inserting of the device 20 in a furnace or the removal thereof from a furnace; and to eliminate allnecessity for applying a wrench to any part of the couple at any time after the device has been initially prepared to be installed in a furnace.

According to the present invention, the thermocouple device 20 is removed from the furnace by a straight axial movement of the tube 2| through the openings 26 and 21, without rotating the tube 2| of the thermo-couple withinthese openings,

For the purpose of fulfilling the object of the invention, the tapered threaded bushing 24 of the base 25 of the device 20 is first threaded into an internally threaded boss of a thread-section of a standard pipe union 3|, which section also includes external threads for cooperation with the internal threads of the ring or nut section of the union. This assembly may be made at any place remote to the furnace.

Into the threaded opening 28, in the back plate 4 of the furnace, is threaded one end of a standard pipe nipple 32. The opposite end of the nipple 32 is threaded into the internal threads of the boss 33 of the second or shoulder-section of the union 3|, which is provided with an annular stepped flange 34 about which is-adapted to revolve the nut or ring section 35 of the union '3 I.

After the nipple 32, with the shoulder-section 33 secured thereto, and with the ring section 35 of the union 3! loosely mounted thereon, is installed in the tapped hole 28 formed in the back wall 13 of the furnace, the thermo-couple device 20 is then put in place, by inserting the tube 2! axially through the bore of the nipple :32, the hole 26 in the insulation 5, and the hole 21 in the rear wall 18 of the mufiie ll, all of which are in axial alignment with each other.

The externally threaded flange 36 of the thread-section 30 of the union 3.1, which has been previously screwed onto the threaded bushing 24 of the couple device 20, is then brought into axially abutting relation'to the shouldered flange section .33 of the union, whereupon the nut section 35 of the union BI is screwed onto the peripheral threads of the flange 35 of the thread-section 30 of the union 31, mtil :a tight joint is formed between these elements, said nut being so arranged as to be rotated about the aligned elements 30 and .33 of the union without necessitating the rotation of either of these elements or the thermocouple xlevice 20 carried by the element 30 of the-union.

The thermo-couple device 210 may be removed from the furnace by reversing the order above recited, i. ;e., by merely loosening and backing ofi the nut .35 from the couple-carrying element an, whereupon the tube .2il may be carefully withdrawn, in a straight line, from the holes .26 and 21 and the nipple 132,,withou-t danger of breaking said tube 2|, or the wires therein in instances Where the tube has been cracked cross-sectionally.

From the foregoing it will be clear that a standard fiange-type union may be used in place of the screw-type previously described, as .shown in Fig. 2. In this instance, one section of a flange union 30a may be threaded onto the projecting end of the nipple 32, and the other sect-ion 33a threaded onto the bushing 24 :of the thermocouple device 20, whereupon the two flanged sections may be secured together by bolts 35a. The procedure in inserting and withdrawing the thermo-couple will be substantially the same in this case as in the case of the mounting shown in Fig. 1.

.,Fr.om the :above, it will be clear that a thoroughly practical and highly improved'detachable multi-sectional couple device including one section stably conmounting for the thermo-couple device may be provided by the use of ordinary standard pipe unions and nipples, at very low cost.

It will also be clear that in removing a thermocouple device from a furnace, when provided with the improved mounting of the present invention, the tube may be gently removed from the furnace wall by careful manual manipulation, in a straight line, once the elements of the mounting have been disconnected, under the removers sense of touch by which the pressure applied to the tube may be delicately controlled and the tube, or wires in the tube, will be spared from breakage, which would be impossible under the prior art practices.

I claim:

1. In a furnace comprising a combustion chamber and a back Wall including an exterior metal plate and having an opening extending from the exterior of said wall to the interior of said combustion chamber for passage of an axially elongated member of a thermowoupl device including :a base structure provided with a shank adjacent the juncture :of the elongated member therewith; the improvement which comprises a mounting for said thermonected to the exterior plate of said wall at the outer end solely of said opening, a section stably secured to said shank, and means for securing said sect-ions together to .afiord axial hon-rotational movement of said elongated member through said opening in applying said thermocouple device to and removing it from said furnace.

,2. In a furnace comprising a combustion chamber and a back wall including an exterior metal plate and having an opening extending from the exterior of said wall to the interior of said combustion chamber for passage of an axially elongated member of a thermo-couple device including .a base structure provided with an externally threaded shank adjacent the juncture of the elongated member therewith, said back wall having a threaded mouth extending through said exterior plate thereof at the outer end of said opening for normally receiving said shank; the improvement which consists of a multi-secticnal mounting for said thermo-couple device including one section having an externally threaded projection screwed into said mouth through said plate, asecond section threaded onto said shank, and means for securing said sections together to aiford axial non-rotational movement of said elongated member through said opening and the first said section of the mounting in applying the thermo-couple device to and in removing it from said furnace.

.3. In a furnace comprising a combustion chamber and a back wall including an exterior metal plate and having an opening extending from the exterior of said wall to th interior of said combustion chamber for passage of an axially elongated member of a thermo-couple device including a base structure provided with an externally threaded shank adjacent the juncture of the elongated member therewith, said back wall having a threaded mouth extending through said exterior plate thereof at the outer end of said opening for normally receiving said shank; the improvement which consists of a multi-sectional mounting for said thermo-couple device including a nipple screwed into said mouth through said plate, a section threaded onto said nipple, a section threaded onto said shank, and means for securing said sections together to afford axial non-rotational movement of said elongated member through said opening said nipple and said first section in applying the thermo-couple device to and in removing it from said furnace.

4. In a furnace comprising a combustion chamber and a back wall including an exterior metal plate and having an opening extending from the exterior of said wall to the interior of said combustion chamber for passage of an axially elongated member of a thermo-couple device including a base structure provided with an externally threaded shank adjacent the juncture of the elongated member therewith, said back wall having a threaded mouth extending through said exterior plate thereof at the outer end of said opening for normally receiving said shank; the improvement which consists of a multi-sectional mounting for said thermo-couple device including a nipple screwed into said mouth through said plate, a section threaded onto said nipple, a section threaded onto said shank, and a rin nut rotatably mounted on one of said sections and having threaded engagement with the other of said sections for securing said sections together to afford axial non-rotational movement of said elongated member through said opening said nipple and said first section in applying the thermo-couple device to and in removing it from said. furnace.

WILLIAM B. LEVY. 

